1. Field of the Invention
The present invention relates to a method for producing a rare-earth sintered magnet, more particularly to a method for compacting a magnetic powder in a magnetic field to improve magnetic orientation.
2. Description of the Related Art
In production of an anisotropic sintered Sm—Co or Nd—Fe—B system magnet, compacting is conducted in a magnetic field. It is important to improve the orientation of the magnetic powder when compacted in a magnetic field, in order to improve the residual magnetic flux density of the anisotropic sintered magnet. A more orientated magnet has a higher squareness, leading to higher residual magnetic flux density and magnetizability thereof.
Japanese Patent Laid-Open No. 61-208809 proposes production of an Nd—Fe—B system sintered magnet, wherein magnesium stearate is used as an additive and a pulsed magnetic field is applied while it is compacted.
Japanese Patent Publication No. 3,307,418 discloses a method for applying a pulsed magnetic field to a compacted body of magnetic powder while it has a relative density of 30 to 55%, discussing that it can have improved magnetic orientation even in the absence of a lubricant or a release agent, e.g., magnesium stearate.